Customized, Ruggedized Screens Up Processing Capacity

Sun April 06, 2008 - National Edition
CEG



By Dave Rizzo

Special to CEG

With the advent of screen manufacturers willing to invest hundreds of man-hours of engineering time and thousands of dollars in materials to create heavy-duty, tailor-made screeners, plant managers and engineers can now receive equipment optimized for their specific operation, without sacrificing the ruggedness previously only available through one-size-fits-all choices. The payoff yields faster installation, increased throughput, less maintenance, and longer equipment life — all of which points to a faster way to profits.

“Before we were running roughly 8 to 12 tons of dry sand per hour into our bins, but with our new customized screener we can run up to 50 tons,” said Rick Hollenbeck, plant supervisor of Bixby, Okla.-based Mountain Creek Materials LLC, a division of Timco Materials.

“We can now process the amount of sand we need to keep up with demand, thereby allowing us to satisfy our customers.”

Growing Demand for Customized Equipment

Despite the softening U.S. economy, the need for processing aggregates and mining materials shows no slackening. For example, Cleveland-based market research firm, The Freedonia Group Inc., predicts that worldwide demand for cement is expected to rise at an annual rate of 4.8 percent through 2008. In response, the aggregates, mining and construction industries’ need for high-output processing equipment keeps rising in lockstep.

“Our old screener wasn’t able to keep up with the amount of dry, bulk sand the dryer put on it,” recalled Hollenbeck. “We couldn’t keep up with demand and suffered monetary losses as a result. “

Yet, settling for off-the-shelf equipment in the rush for increased throughput or ruggedness often entails extra expense and slowdowns in integrating such inflexible equipment into the operation. In contrast, customized screening solutions involving already heavy-duty equipment allows the most appropriate “set-up” for a long-term balance of efficiency and output. In effect, plant managers can get the best of both worlds.

Customization — A Process Unto Itself

Creating a custom-made piece of equipment begins with research. A screen manufacturer must carefully collaborate with the plant builder or the operations manager to correctly qualify and quantify his or her needs.

“We needed a 50-ton, two-screen classifier that would sit on top of the bin,” explained Hollenbeck. “Since it handled dry sand, it had to be sheltered from the elements. But with the screen so high up in the air, building a house around it would have been a mess.

However, the folks at SMICO were willing to customize a machine that would do this for us. They designed and built a cap that made it completely watertight.”

SMICO Manufacturing Company Inc. of Oklahoma City, Okla., provides both stock and customized screening and sifting equipment to various industries, including aggregate, mining, construction, stone, clay, glass and concrete. The company’s product line includes conveyors, separators, feeders, sifters and vibrating screeners ranging in sizes from 12 in. by l ft. to 8 in. by 20 ft. (30 cm by 0.3 m to 20 cm by 6 m).

The company begins by collecting pictures, drawings, blue prints and material samples — the latter of which is analyzed in the company’s on-site test facility. Given its 70-year history of evaluating materials, the company passes along its non-recurring engineering savings onto the customer.

Starting with this information, the process of customizing screens — especially for retrofit applications — continues with the consideration of three “F” words in engineering: form, fit and function.

Form

Modifications to conform to the profile and footprint of any screener should ideally be undertaken by the manufacturer of the equipment, not the end user. For example, moving the drive to the center of the machine, as opposed to the more standard top location, can help fit a large screen into a factory with a low roof. Linear-design screeners represent another example of separation equipment and vibration shakers that are particularly suitable for space, weight, and clearance issues.

Screens with side-parallel conveying motion also allow leeway in form, as they can be manufactured in variable sizes from 3 to 8 ft. wide (0.9 to 2.4 m) and from 6 to 20 ft. (1.8 to 6 m) long.

Fitting

Perhaps the most challenging aspect of customizing equipment is fitting it into existing mountings. After-the-fact adjustments of conveyors and other feed and take-away systems can slow down the process of installation, and, at worst, result in inefficient material handling. The best of customizers are willing to do the up-front work to make sure the new screener drops readily into place when delivered. For instance, screeners should offer a choice between suspension or base mounting.

“Installation of our customized screener was really easy,” said Hollenbeck. “We literally just lifted it up off the trailer, set it down, and hooked the electricity up to it.”

Function

For direct replacement, the exact duplication of function stands as the overarching goal. Today’s demands to push through greater volumes, though, often dictate increased functionality over that of the original screen. Again, customized equipment most readily fills the bill.

Here, the equipment designers must select the drive and method of screening that best fits the application at hand. If maximum throughput is the objective, then rectangular screens prove the better choice over round, as the rectangular design consistently yields greater throughput given the same amount of surface area, according to the manufacturer.

Harsh environments, of course, scream out for application-specific screeners. Take the case of mine tippers (breakers), where there is usually much structural movement. By employing a 2-bearing, positive eccentric, oil-lubricated screener design, SMICO, for one, manages the abuse by allowing the screen surface to wobble within its spring-mounted casing. In this manner these “GYROSETS” absorb tremendous shock and continue operation with little maintenance. Adjustable pitch. and eight different strokes increase their application-specificity.

“Each one of the SMICO screen towers can be customized for the particular application at hand; it makes it easy to work with that way,” commented Jim Hurlburt, head engineer for Meeker Equipment, a manufacturers representative with headquarters in Lansdale, Pa.

The best of these products go even beyond the three basic parameters — adding ruggedness, timeliness of delivery and cost-effectiveness — to save an aggregate or mining operation even more money.

For instance, dual-deck vibrating screeners can be ruggedized with four bearings, as opposed to two, to ensure that it is able to handle demanding Tonnage Per Hour requirements. For extreme cases, SMICO selects bearings the way mil-spec parts were selected: by only accepting the top 10 percent of the run.

The use of hardened materials such as A516 carbon steel adds to a screen’s increased strength and durability, allowing future refurbishing that can keep a screen operating in the field for 15 to 20 years or longer.

“I’ve never seen an issue with plugging and blinding using the SMICO units,” continued Hurlburt.

“We mainly apply their equipment in recycled asphalt systems and for some of virgin aggregate systems. Most recently, we ordered some for our project in Long Island, N.Y. We typically opt for the incline, overhead eccentric type screen. It works well as a scalping machine, and it’s good value for the price.”

Lastly, no matter how good a machine is, if delivery lags then the customer loses money. Even with customized attributes, the timelines for screens should fall within a 6 to 10 week period, no longer.

“We had customers waiting, so we wanted to get the screener in on a certain weekend,” said Hollenbeck. “SMICO worked overtime to meet our deadline.”

Customization That Pays for Itself

When a plant manager and engineer can simply and quickly integrate the optimized screener into the process, they stand to save their company money in both the short run and over the long haul. Toss ruggedization into the mix and customized solutions help aggregate, mining and construction operations yields greater production and quicker profits.

For more information, call 800/351-9088 or visit www.SMICO.com.